Dirty diesel

In the 19th century, John Snow correctly identified the Broad Street pump as the source of a cholera outbreak in Soho, but a subsequent inquiry by the Board of Health decided that there was no reason to act.1

The response of the UK government to air pollution displays a similar lack of foresight. The main problem is diesel. Not only do we have a legacy of dirty lorries, buses, and taxis; the UK, along with much of Europe, has tragically adopted diesel as the main fuel for private cars. Before 2000 less than 10% of new cars sold in the UK were diesel. Now the figure is over 50%. Furthermore the amount of nitrogen dioxide (NO₂) emitted by most diesel cars on the road is 4-5 times the EU limits allowed in laboratory tests. Illegal defeat devices installed by Volkswagen enabled NO₂ emissions up to 40 times the EU limit.

For the past six years, the UK government has refused to implement the 2008 EU Air Quality Directive on the grounds …